On the early morning of 16 October 2018, signalling faults occurred on the Island (ISL), Tsuen Wan (TWL), Kwun Tong (KTL) and Tseung Kwan O (TKL) Lines. The Electrical and Mechanical Services Department (EMSD) immediately deployed staff to monitor the recovery works and investigation. The EMSD subsequently reviewed the signalling system data records on the incident day and observed the simulation test conducted by the MTR Corporation Limited (MTRCL) and overseas experts from the signalling system suppliers.
According to the investigation results, the signalling systems of the ISL, TWL, KTL and TKL were provided by two suppliers. The two systems of the four lines were interconnected through sector computers. To ensure communication between the two systems for delivery of train control commands, the data transmission must be synchronised at all times. Due to the difference in the software counter re-initialisation arrangements of the two systems, an unco-ordinated situation occurred between the two interconnected systems when undergoing synchronisation as usual on the morning of 16 October (i.e. the incident time), resulting in unstable operation (i.e. unable to deliver stable train control commands). After the MTRCL isolated the connections between relevant lines and rebooted all computers, the signalling systems of the four lines resumed normal. The incident had no correlation with the signalling system upgrading project and its testing.
The EMSD requested the MTRCL to conduct a comprehensive examination of the signalling system equipment, and continue to closely monitor and maintain the relevant systems during the signalling system upgrading project and its testing, including deploying additional personnel when necessary to stand by in critical stations' signalling equipment rooms to reboot the computers and expedite the recovery works. The MTRCL was also requested to conduct review and implement a maintenance programme to manually re-initialise all software counters in the railway systems, particularly the signalling systems, before they reach the triggering or ceiling figure. In addition, the MTRCL was requested to establish a dedicated team with experts from the academia and the industries to enhance software integration and performance for new railway systems and modifications of critical railway systems.